Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$190.50	3.403%	$196.9827	$196.98	$197.00	$197.00
Purchase #2	$231.34	5.602%	$244.2997	$244.30	$244.30	$244.30
Purchase #3	$165.69	11.575%	$184.8686	$184.87	$184.85	$184.90
Purchase #4	$244.38	8.463%	$265.0619	$265.06	$265.05	$265.10
Purchase #5	$20.33	9.678%	$22.2975	$22.30	$22.30	$22.30
Purchase #6	$76.89	11.297%	$85.5763	$85.58	$85.60	$85.60
Purchase #7	$239.31	7.261%	$256.6863	$256.69	$256.70	$256.70
7 purchase totals =	$1,168.44		$1,255.7730	$1,255.78	$1,255.80	$1,255.90